Portable hand-held screw driving tools have been available from Senco Products, Inc. and DuraSpin Products LLC for several years. These tools typically include a movable front end that was essentially depressed into the remaining portion of the tool by pressing the front end of the tool against a solid object that will receive the screw. The movable portion of the previous tools has been referred to as a movable “nose piece,” which also had a slide body sub-assembly that is fixedly attached to the nose piece, thereby moving the slide body sub-assembly at the same time the nose piece moved, relative to the housing of the tool. As the nose piece and slide body sub-assembly move, a screw is indexed to a drive position, the head of the screw is engaged against the front end of a drive bit, and later the drive bit is rotated to cause the screw to rotate while it is emplaced into the solid object.
The initial movement of the tool could be referred to as a first stage of movement, during which the screw is indexed to the drive position (note that this is for an indexed on advance arrangement), and the drive bit is engaged within the slot or recess of the screw head. During the first stage, the drive bit is not intentionally rotated to any significant amount, perhaps only a small amount so as to ensure its proper alignment into the slot or recess of the screw's head. Then during a second stage of movement, the motor inside the portable tool is energized, and the drive bit is then rotated to drive the screw into the object.
In the previous Senco/DuraSpin tools, these two stages of movement caused the nose piece with slide body sub-assembly to linearly “collapse” into a “feed tube” that itself was fixedly attached to the housing of the portable tool. Since the feed tube was not movable with respect to the housing, the feed tube itself had a dimension that would contact a surface of a wall when the tool was used to drive a screw near the corner of two adjoining walls. The distal (i.e., front) end of the feed tube and the distal (or front) end of the housing were the primary constraints on locating a screw as close to the corner as possible.